Self-emitting display devices, such as of the CRT type, provide a video image by the bombardment of phosphor elements disposed on the inner surface of the device's display screen by high energy electrons. The phosphor elements are separated into three groups, with each group emitting one of the primary colors of red, green or blue when impinged upon by the energetic electrons. For optimum color purity, the three groups of color phosphors should emit light characterized by three discrete spectra, with no overlap between adjacent spectral components. In practice, however, there is always some color spectrum overlap between adjacent primary color phosphors, i.e., between red and green as well as between green and blue. The spectral regions of overlap between red and green typically covers wavelengths in the range of 460-500 nm, while spectral overlap between the colors green and blue typically includes wavelengths in the range 560-600 nm. Any spectral overlap between the primary colors degrades video image color purity and color contrast.
U.S. Pat. No. 4,987,338 to Itou, et al. discloses an antistatic/antiglare coating in the form of a single layer to which an organic dye is added. This approach is not particularly desirable because the organic dye is subject to bleaching out of the coating when the faceplate is wiped with a wet cloth containing either water or alcohol. More recently, U.S. Pat. No. 5,291,097 to Kawamura, et al. teaches the addition of an organic dye to the inner antistatic layer of a double-layer antireflective/antistatic coating on the outer surface of the CRT's faceplate. The inner antistatic layer containing the organic dye is then covered with the outer antireflective layer. Even in this approach where the inner antistatic layer is covered by a protective outer antireflective layer, the organic dye has been observed to diffuse outwardly from the inner antistatic layer and through the outer antireflective layer, with the organic dye eventually bleaching out of the antireflective/antistatic coating on the faceplate through repeated wiping of the faceplate with either a dry or wet cloth.
The present invention addresses the aforementioned limitations of the prior art by permanently bonding an organic dye to silane in either the outer antireflective layer or the inner antistatic layer in preventing the bleaching of the dye from the surface coating. The organic dye functions as a color spectrum filter between two adjacent primary color phosphors so as to substantially eliminate primary color overlap resulting in improved color contrast and purity.